Incandescent bulbs don't contribute as much heat as unshaded windows, but they do add heat to a house and can raise the perceived temperature, sending you to the thermostat to seek relief. To reduce this hot-light effect and save lighting costs year-round, replace incandescent bulbs with compact fluorescents. They use about 75 percent less energy and emit 90 percent less heat.
Cost: $12 to $25 per bulb
Benefit: Up to 5 percent off your cooling bill plus electricity savings